There are a number of processes for converting lignocellulosic biomass into liquid streams of various fermentable sugars. Certain preferred processes are based on supercritical water (SCW) or hot compressed water (HCW) technology, which offer several advantages including high throughputs, use of mixed feedstocks, separation of sugars, and avoidance of concentrated acids, microbial cultures, and enzymes. Processes using hot compressed water may have two distinct operations: pre-treatment and cellulose hydrolysis. The pre-treatment process hydrolyzes the hemicellulose component of the lignocellulosic biomass and cellulose hydrolysis (CH) process, as its name infers, hydrolyzes the cellulose fibers. The resultant five carbon (C5) and six carbon (C6) sugar streams are recovered separately. The remaining solids, which consist mostly of lignin, are preferably recovered, such as through filtration, and may be used as a fuel to provide thermal energy to the process itself or for other processes.
Among their many uses, the sugar streams may be converted to ethanol through fermentation using yeast or bacteria that feed on the sugars. As the sugars are consumed, ethanol and carbon dioxide are produced.
The invention is directed to these compositions, as well as and other important ends.